<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
  <input type="text" v-model="n1">
  <input type="text" v-model="n2">
  <input type="button" value="加" @click="f(1)">
  <input type="button" value="减" @click="f(2)">
  <input type="button" value="乘" @click="f(3)">
  <input type="button" value="除" @click="f(4)">
  <h3>结果:{{result}}</h3>
</div>
<script src="js/vue.min.js"></script>
<script>
  let v = new Vue({
    el:"body>div",
    data:{
      n1:"", n2:"", result:""
    },
    methods:{
        f(x) {
            if(isNaN(v.n1) || isNaN(v.n2)) {
                v.result = "输入错误!"
                return;
            }
            switch(x) {
                case 1:
                    v.result = parseFloat(v.n1) + parseFloat(v.n2);
                    break;
                case 2:
                    v.result = v.n1 - v.n2;
                    break;
                case 3:
                    v.result = v.n1 * v.n2;
                    break;
                case 4:
                    v.result = v.n1 / v.n2;
                    break;
            }
        }
    }
  })
</script>
</body>
</html>